Pure Virtual Function in C++ Explained

A pure virtual function in C++ is a virtual function declared in a base class but has no implementation, indicated by adding “= 0” after the function declaration. This is used to define an interface, forcing subclasses to implement the function to achieve polymorphism.

Pure virtual functions are often used to define an abstract base class that contains interfaces that must be implemented by subclasses, but the base class itself does not need to provide concrete implementations. Subclasses must implement the pure virtual functions in the base class, otherwise the subclass will also be considered an abstract class and cannot instantiate objects.

Using pure virtual functions can achieve the following objectives:

1. Define an abstract base class that enforces subclasses to implement specific interfaces.
2. Allowing polymorphism enables different subclasses to have different implementations.
3. Implement interface segregation, separating different implementations to improve the maintainability and flexibility of the code.

In conclusion, pure virtual functions are an important tool in C++ for implementing abstract base classes and polymorphism.